The Churchyard of Saint Gertrude at first was a cemetery for the local hospital, later also for a provincial parish and from 1791 has been the central cemetery for Oldenburg, a very old city off the northwestern coast of Germany in the state of Lower Saxony (Niedersachsen). It has long been the burial place of well-known families. Today its use is through the Evangelical (Lutheran) Parish of Oldenburg. It is about 2.5 hectares big and has over 13,000 graves. This graveyard has the longest surrounding wall, of a classic type, in the so called Oldenburger province, built in 1646, and also the largest regional collection of historic art and sculptures from various epochs, styles and materials for its many different symbolic monuments. The park-like and diversified planting, begun in 1842 under French influence, is now important to over 30 species of birds and bats. The linden trees in front of the chapel, according to legend, have long grown there in honor of the virtue of a particular deceased maiden. The Ducal (Herzogliches) Mausoleum was begun in 1786, in memory of Duchess Frederica who died in childbirth, and completed in 1899. It is still the place of interment of the ducal branch of the Oldenburg Dynasty and is closed to the public. Decorations are sculptures by Dannecker, memorial texts on the walls by Klopstock and Stolberg, as well as stucco ornamentation by F. A. Högl. St. Gertrude's Chapel was first mentioned in documents in 1428, built in front of the town gate for its hospital and named for the Holy Gertrude of Nivelles (Belgium), a 7th century abbess and patron of pilgrims, the disea sed and the souls of the dead. It features mediaeval frescos telling her life story, severely damaged by fire in 1985 and later only partially restored. During renovation work then, ancient grave vaults were discovered and restored, but they are not accessible. Later appointments in the chapel are of modern origin, including a new organ from 1991, and it is still in use for weddings, christenings and funerals.